DE102014201974A1 - Method for operating an automatic transmission and control device for carrying out the method - Google Patents

Abstract

Method for operating an automatic transmission (3) of a motor vehicle, wherein the automatic transmission (3) has a plurality of lockable switching elements (6), wherein from data available during driving of the motor vehicle by a activated locking of switching elements (6) probably caused consumption change of the motor vehicle and a is probably evaluated by an activated locking of switching elements (6) caused shift dynamics change of the motor vehicle is assessed such that depending on the change in consumption and depending on the switching dynamics change a locking of switching elements (6) is allowed or not allowed.

Description

The invention relates to a method for operating an automatic transmission and a control device for carrying out the method.

Automatic gearboxes known from practice for motor vehicles have a plurality of shifting elements, wherein in each gear of the automatic transmission a first number of shifting elements are closed or switched on and a second number of shifting elements are opened or switched off. For opening and closing, the switching elements of known from practice automatic transmissions are hydraulically actuated, namely typically such that when no or on the respective switching element is applied too low hydraulic pressure, the respective switching element is open, whereas, if sufficient on the switching element high hydraulic pressure is applied, the respective switching element is closed.

Automatic transmission with such hydraulically actuated switching elements are, for example, from DE 10 2007 055 808 A1 as well as from the DE 10 2008 000 429 A1 known.

From the DE 102 44 523 A1 For example, it is also known to lock hydraulically actuated shift elements of an automatic transmission in the closed state via a locking device or locking device, so that the respective switching element remains closed even when the hydraulic actuation pressure is reduced.

From the DE 103 04 050 A1 is a hydraulically actuated switching element of an automatic transmission with a mechanical locking device or locking device known.

From the EP 1 995 484 B1 is a hydraulically actuated switching element of an automatic transmission with an electric motor or electromagnetically actuated locking device or locking device known.

As stated above, when a hydraulically operated switching element is locked in the closed state via a locking device or latching device, the respective switching element can be kept closed even if a hydraulic actuating pressure, which is actually required to close the respective switching element , is mined. This has the advantage that then a receiving torque of an oil pump, which serves to provide a hydraulic actuation pressure, can be reduced, so that ultimately the consumption of the motor vehicle can be reduced.

Then, when a shift element of an automatic transmission is locked, to open the same, the lock must be released, which requires it to open the respective locking device. As a result, when opening a previously locked switching element delay times can form, which affect a switching dynamics of the automatic transmission.

There is a need for a method for operating an automatic transmission of a motor vehicle, by means of which a lock for lockable shift elements of the automatic transmission can be suitably approved or not approved and thus can be selectively activated or deactivated.

On this basis, the object of the present invention is to provide a novel method for operating an automatic transmission and a control device for carrying out the method.

This object is achieved by a method for operating an automatic transmission according to claim 1.

According to the invention, a consumption change of the motor vehicle which is likely to be brought about by an activated locking of shifting elements and a shifting dynamics change of the motor vehicle probably caused by an activated locking of shifting elements is evaluated such that depending on the change in consumption and depending on the shifting dynamics change, a locking of Switching elements allowed or not allowed.

In the method according to the invention, the presumably caused by an activated locking of switching elements consumption change of the motor vehicle and estimated by an activated locking of switching elements switching dynamics change of the motor vehicle is evaluated, so depending on the consumption change and the switching dynamics change a locking of switching elements allowed or not approved or a Locking of switching elements is activated or deactivated. This makes it particularly advantageous possible to allow the locking of switching elements purposefully or not to allow or disable or disable either to provide higher switching dynamics at higher consumption or lower consumption with less switching dynamics.

According to an advantageous development of a locking of switching elements is then allowed or activated when the motor vehicle is not operated in overrun, and / or if the Motor vehicle is not braked, and / or if the motor vehicle is operated at a constant speed, and / or if a transmission temperature is neither too high nor too low, and / or if a driving or switching program allows the activation of the lock, and / or if a sufficiently long time is available until the next switching request, and / or if an energy balance is active when the lock is activated, and / or if there is a low driver-side driving activity, and / or if a spontaneous driver-side power request is unlikely. Then, if none of these conditions is met, the locking of switching elements is not allowed or disabled and thus terminated. The number and type of the above conditions, which are used in carrying out the method according to the invention are dependent on the specific configuration of the motor vehicle. The above conditions can be used in any combination with each other.

According to a further advantageous development, if the locking of switching elements is not permitted or deactivated or terminated, subsequent activation is permitted again only after a defined period of time has elapsed. Such debouncing can be prevented that a required switching dynamics is unduly reduced by activating a locking of switching elements.

The control device according to the invention is defined in claim 13. Preferred developments emerge from the subclaims and the following description. Embodiments of the invention will be described, without being limited thereto, with reference to the drawings. Showing:

1 a powertrain diagram of a motor vehicle. The present invention relates to a method for operating an automatic transmission of a motor vehicle.

1 shows very schematically a drive train scheme of a motor vehicle, according to 1 between a drive unit 1 and a downforce 2 an automatic transmission 3 is switched, which speeds and torques converts and so the traction power supply of the drive unit 1 at the output 2 provides. The operation of the drive unit 1 is via a motor control device 4 and the operation of the automatic transmission 3 is via a transmission control device 5 controlled according to what 1 the engine control device 4 with the drive unit 1 and the transmission control device 5 with the automatic transmission 3 exchanges data in the sense of the double arrows shown. Similarly, change the engine control device 4 and the transmission control device 5 with each other data. The automatic transmission 3 includes several switching elements 6 , where in 1 only such a switching element 6 is shown as an example. The in 1 shown switching element 6 is a locking device 7 assigned, via which the switching element 6 can be locked in the closed state, wherein it is in such a locking device 7 For example, it may be a mechanical locking device or a hydraulic locking device or an electromotive locking device or an electromagnetic locking device.

The invention now relates to a method for operating such an automatic transmission 3 with lockable switching elements 6 , with the help of which a locking of switching elements 6 purposefully approved or not approved or a locking of switching elements 6 purposefully activated or deactivated.

From the driving operation of the motor vehicle available data becomes one by an activated locking of switching elements 6 probably caused consumption change of the motor vehicle and one by an activated locking of switching elements 6 probably caused switching dynamics change of the motor vehicle evaluated such that depending on the change in consumption and depending on the switching dynamics change a locking of switching elements 6 of the automatic transmission 3 approved or not approved or a locking of switching elements is activated or deactivated. According to the invention, therefore, a balance is made between the interests of the lowest possible consumption of the motor vehicle and the highest possible switching dynamics of the latter, in order to depend on this the locking of switching elements 6 of the transmission 3 purposefully allow or not.

According to an advantageous embodiment of the method according to the invention is a locking of switching elements 6 of the automatic transmission 3 only allowed or activated if the motor vehicle is not operated in overrun mode and / or if the motor vehicle is not braked and / or if the motor vehicle is operated at a constant driving speed and / or if a transmission oil temperature is neither too high nor too low, and / or if a drive or shift program permits activation of the lock and / or if sufficient time is available for the next shift request and / or if an energy balance with lock enabled is positive and / or if there is a low driver-side drive activity and / or when a spontaneous driver-side power request is unlikely.

Preferably, the above new conditions, depending on which the locking of the switching elements 6 of the automatic transmission 3 approved or not, in combination with each other. Depending on the specific configuration of the motor vehicle, however, only some of these new conditions may be evaluated or evaluated in combination with each other.

Then, if latching of switching elements is enabled, some or more of the above conditions, if not met, may also result in deactivating and terminating an enabled latch.

After a first of the above conditions, the locking of switching elements of the automatic transmission is only allowed or activated when the motor vehicle is not operated in overrun mode. A motor vehicle is preferably not operated in overrun mode when an engine torque of the drive unit 1 of the motor vehicle is greater than a defined limit and / or if a turbine torque of the automatic transmission 3 of the motor vehicle is greater than a defined limit. Thus, in overrun operation, an increased intake torque of an oil pump does not directly lead to an increased consumption of the motor vehicle, but rather to an increased coasting deceleration. Due to the increased absorption torque of the oil pump, a service brake can be relieved.

A second, additional or alternative condition, depending on which the locking of the switching elements 6 of the automatic transmission 3 admitted or not permitted or activated or deactivated, provides that the locking of switching elements is only allowed if the motor vehicle is not braked. The motor vehicle is preferably not braked when a service brake is not actuated by the driver, or when a driver assistance system, such as the ACC system or an ESP system, does not brake or does not actuate the service brake and / or if a sum of all wheel drive torques is greater than is a limit.

According to a third, additional or alternative, condition is provided that the locking of the switching elements 6 of the automatic transmission 3 of the motor vehicle is only allowed or activated when the motor vehicle is operated at a constant driving speed. A constant driving speed is preferably present when the driving speed of the motor vehicle lies within a defined range for a defined period of time and / or when the acceleration of the motor vehicle lies within a defined range within a defined period of time. Then, when a motor vehicle is operated at a nearly constant driving speed, the execution or request of circuits is unlikely, so then activating the locking of switching elements 6 an automatic transmission 3 makes sense.

According to a fourth, additional or alternative, condition is provided that the locking of the switching elements 6 of the automatic transmission 3 is only permitted or activated if a transmission oil temperature is neither too high nor too low. This condition is preferably fulfilled when, in particular, a transmission oil sump temperature is within a defined temperature range. This condition is based on the finding that at low transmission temperatures, a filling of switching elements takes a relatively long time, so that a response to a circuit request should not be additionally delayed by the locking of the switching elements. If the transmission temperatures are too high, the leakage of the locking devices can occur 7 be increased, so then an activation of the same does not make sense.

After a fifth, additional or alternative, condition is provided that the locking of switching elements is only allowed or activated when a driving or switching program allows the activation of the lock. For example, a drive or shift program of the transmission control device 5 then not allow the lock when a sports driving program or an off-road driving program or a manual shift program is active, or if in a motor vehicle, the automatic transmission is designed as a transfer case or as a group transmission in one of the range group of the automatic transmission low Gear is engaged.

After a sixth, additional or alternative, conditions is provided that the locking of the switching elements 6 of the automatic transmission 3 is then allowed or activated if a sufficiently long time is available until the next switching request. For this purpose, via a switching point prediction of a switching program of the transmission control device 5 a time is available, which is available until the execution of the next circuit. If this period of time is sufficiently large, ie greater than a limit value, the activation of the locking of the switching elements 6 of the automatic transmission 3 authorized. In this case, therefore, a sufficiently long period of time is available in which the consumption-improving effect of a switching element interlocking can be utilized.

After a seventh, additional or alternative, condition is provided, the locking of the switching elements 6 then admit, if one Energy balance with activated locking is positive. This condition is met when one for locking and then unlocking the locking devices 7 and thus the switching elements 6 the amount of energy required is less than an energy saving achievable between the locking and unlocking thereof by the lock. This condition is based on the finding that the locking and subsequent unlocking of a locking device 7 and thus a switching element 6 via an increase in pressure. For this purpose, compared to the operation of the automatic transmission without locking an additional amount of energy required, which should be contrasted with those energy savings when driving with active locking of the switching elements 6 and lowered hydraulic pressure arises. An appropriate energy balance then indicates whether the relevant energy balance is positive and the locking of the switching elements from an energetic point of view is worthwhile.

After an eighth, additional or alternative, condition is provided, the locking of the switching elements 6 a gearbox 3 only allow or activate if there is a low driver-side driving activity. This condition is preferably met when a driver-side accelerator pedal operation and / or a temporal gradient of the driver-side accelerator operation are within a defined range and / or when a turn signal is not set on the driver side.

If an accelerator pedal on the driver side is operated heavily or with a high gradient, circuits in the range of the upper speed limit should not be delayed, so that activation of the shift element interlock is then not permitted.

Then, when a relatively large positive time gradient of the accelerator operation is detected, downshift requests are likely.

Then, when there is a relatively large negative time gradient of the accelerator operation, it is likely to change to the brake and thus to shift back on deceleration. In this case, the activation of the switching element interlocking does not make sense.

Then, if a turn signal is set on the driver side, this can be interpreted as a high driving activity, since then a passing or turning operation is likely. Also in this case, the activation of a switching element interlocking does not make sense.

Likewise, then can be concluded on a high driver-side driving activity when a driver's hands are in the vicinity of an actuator for manual circuit activation. For example, it can be detected via a near-field sensor, which is assigned, for example, in the area of a steering wheel built paddles, whether the hands of the driver are in the vicinity of the shift paddles. In this case, an early circuit request is then likely, so then the activation of the switching element interlocking does not make sense and is not allowed.

According to a ninth, additional or alternative condition, it is contemplated that activation of the shift element interlock will only be allowed if a spontaneous driver side power request is unlikely. A spontaneous driver-side power demand is preferably determined on the basis of data of the route and / or on the basis of data of the driving situation, wherein a spontaneous driver-side power request is unlikely, especially if a passing-ban is detected by a navigation system or a traffic signal recognition system for the route if an overtaking maneuver is unlikely. Here also data about the weather can be considered.

This ninth condition is based on the recognition that a spontaneous acceleration request and thus a spontaneous driver-side power requirement is unlikely when a vehicle overtaking ban is detected on the basis of route data stored in a navigation system and / or based on driving route data recognized with the aid of a traffic sign recognition system.

Furthermore, it is possible to conclude an improper overtaking operation based on a speed limit, in particular when the motor vehicle is traveling at a driving speed which is within the range of the speed limit.

Furthermore, oncoming traffic can be detected in order to estimate the likelihood of overtaking on the basis of oncoming traffic. The more oncoming traffic, the less likely is an overtaking process and thus a spontaneous demand for power by the driver.

Likewise, a spontaneous acceleration request or spontaneous driver-side power demand is unlikely when available weather data indicate rain, snow or ice.

In contrast, a spontaneous driver-side power request is then likely and activation of the locking of the Switching elements then not allow if the route data, for example by canceling a speed limit, likely to be an acceleration phase for the motor vehicle.

Likewise, due to travel route data, an acceleration phase may be likely, especially if a transition from a winding road to a straight line is detected.

Further, a spontaneous power demand by the driver is likely when overtaking is likely, which may be the case, for example, when the motor vehicle travels behind a preceding vehicle whose speed is significantly lower than a permitted maximum speed, and further when there is no oncoming traffic on the basis of which an overtaking process is unlikely.

If, on the basis of one or more of the above conditions, an activation of the locking of the switching elements is not permitted or a switching element locking is deactivated or terminated, it can be provided that subsequent activation takes place only after a defined period of time has elapsed, which can also be referred to as filter time or debounce time to let in again. In this way it can be ensured that a switching dynamics is not unduly limited by the activation of the switching element locking.

Thus, for example, in a so-called gap jumping, ie in successive overtaking on country roads, a vehicle repeatedly operated depending on the traffic situation and depending on oncoming traffic for a certain time at a constant speed, before the next overtaking is possible. In this case, a sufficient switching dynamics must then be ensured by deactivating or by not allowing the switching element interlock.

As already stated, it is provided in one embodiment of the method according to the invention not to allow activation of the switching element interlocking when overtaking is possible and probable.

The possibility of an overtaking process can be recognized, for example, by evaluating travel route data, for example, about the number of available lanes, oncoming traffic data, traffic flow data, data on a preceding driving route, such as the topography of the route ahead Possibility of overtaking. Furthermore, acceleration reserves, speed limits and no overtaking bans can be taken into account to decide whether an overtaking operation is possible or impossible or likely or unlikely.

To determine the likelihood of an overtaking process, data on the driver's past driving behavior and / or on vehicles ahead of the vehicle and / or behind the vehicle driving vehicles and / or on weather conditions and / or current driver activities, such as setting a turn signal, and / or on current operating parameters of the vehicle are taken into account. The current operating parameters of the vehicle can z. B. depending on whether the vehicle pulls a trailer and / or how high the total weight of the vehicle as a result of a load is the same.

The present invention further relates to a control device for carrying out the method. This control device is preferably the transmission control direction 5 ,

The control device comprises means for carrying out the method according to the invention. These resources are hardware and software resources.

The hardware-side means are data interfaces in order to exchange data with the modules performing the method according to the invention. Furthermore, the hardware means are a processor and a memory, a memory for storing data and a processor for processing data.

The software resources are program modules for carrying out the method according to the invention.

LIST OF REFERENCE NUMBERS

1

power unit

2

output

3

automatic transmission

4

Motor controller

5

Transmission control device

6

switching element

7

locking device

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102007055808 A1 [0003]
• DE 102008000429 A1 [0003]
• DE 10244523 A1 [0004]
• DE 10304050 A1 [0005]
• EP 1995484 B1 [0006]

Claims (13)

Method for operating an automatic transmission of a motor vehicle, wherein the automatic transmission has a plurality of lockable switching elements, characterized in that from the driving data of the motor vehicle available data expected by an activated locking of switching elements consumption change of the motor vehicle and an activated locking of switching elements probably caused switching dynamics change of the motor vehicle is evaluated such that depending on the change in consumption and depending on the switching dynamics change a locking of switching elements is allowed or not allowed. A method according to claim 1, characterized in that a locking of switching elements is allowed when the motor vehicle is not operated in overrun mode, wherein the motor vehicle is not operated in overrun, in particular when an engine torque of a drive assembly of the motor vehicle and / or a turbine torque of Automatic transmission is greater than a defined limit. A method according to claim 1 or 2, characterized in that a locking of switching elements is allowed when the motor vehicle is not braked, the motor vehicle is not braked especially when the driver side, a service brake is not operated or a driver assistance system does not brake and / or a sum of all wheel drive torques is greater than a limit. Method according to one of claims 1 to 3, characterized in that a locking of switching elements is allowed when the motor vehicle is operated at a constant travel speed, the motor vehicle is operated in particular at a constant travel speed, when the vehicle speed is and / or the acceleration within a defined time in a defined range. Method according to one of claims 1 to 4, characterized in that a locking of switching elements is allowed when a transmission temperature is neither too high nor too low, wherein the transmission temperature is in particular neither too high nor too low, if a transmission oil sump temperature in a defined area lies. Method according to one of claims 1 to 5, characterized in that a locking of switching elements is allowed when a driving or switching program allows the activation of the lock, wherein a driving or switching program allows the activation of the lock, in particular if neither a sports driving program nor an off-road driving program nor a manual shifting program is active. Method according to one of claims 1 to 6, characterized in that a locking of switching elements is allowed when a sufficiently long time is available until the next switching request, in particular then until the next switching request a sufficiently long time is available, if A shift point prediction of the drive or shift program calculates that a time period available until the next shift request is greater than a limit value. Method according to one of claims 1 to 7, characterized in that a locking of switching elements is allowed when an energy balance with activated locking is positive, in particular, then an energy balance with activated locking is positive when needed for locking and subsequent unlocking Amount of energy is less than a recoverable between locking and unlocking energy savings. Method according to one of claims 1 to 8, characterized in that a locking of switching elements is allowed when there is a low driver-side driving activity, in particular then a low driver-side driving activity is present when a driver-side accelerator pedal operation and / or a time gradient of the driver-side accelerator pedal operation lies in a defined range and / or a turn signal driver side is not set. Method according to one of claims 1 to 9, characterized in that a locking of switching elements is allowed when a spontaneous driver-side power request is unlikely, with a spontaneous driver-side power requirement of data of the route and / or the driving situation is dependent and in particular is unlikely if overtaking is detected by a navigation system or a traffic sign recognition system for the route, and / or if an overtaking maneuver is unlikely. Method according to one of claims 2 to 10, characterized in that, if none of these conditions is met, the locking of switching elements is not permitted and / or terminated. Method according to one of claims 1 to 11, characterized in that when the locking of switching elements is not allowed or terminated, subsequent activation is permitted again only after a defined period of time. Control device, in particular transmission control device ( 5 ), characterized by means for carrying out the method according to one of claims 1 to 12.

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